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#include <functional> struct A { int func(int x, int y) { return x+y; } }; int main() { typedef std::function<int(int, int) > Funcp; A a; //Funcp func = std:::bind(&A::func, &a); Funcp func = std::bind(&A::func, a, std::placeholders::_1); return 0; } I am getting errors in both of the above bind functions:
error C2825: '_Fty': must be a class or namespace when followed by '::' Where is the syntax error? I am using visual studio 2010
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Case 2: You want the class to have an instance, you first need to create an object so that the class has an identity, once that is done you can use the object his methods. Myclass m; m. printInformation(); // Or, in the case that you want to use pointers: Myclass * m = new Myclass(); m->printInformation();
Using a pointer-to-member-function to call a function Calling the member function on an object using a pointer-to-member-function result = (object. *pointer_name)(arguments); or calling with a pointer to the object result = (object_ptr->*pointer_name)(arguments);
Many std::function implementations will avoid allocations and use space inside the function class itself rather than allocating if the callback it wraps is "small enough" and has trivial copying.
If it is small, like 3-5 CPU instructions then yes std::function will make it slower, because std::function is not inlined into outer calling code. You should use only lambda and pass lambda as template parameter to other functions, lambdas are inlined into calling code.
Funcp func = std::bind(&A::func, &a, std::placeholders::_1, std::placeholders::_2); If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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